NASA’s Voyagers: 35 years of inspiration

The two Voyager probes changed how we view science and the Universe.

August 20, 1977 turned out to be a before-and-after moment for me—and probably a lot of other people as well. None of us knew it at the time, though, since the launch of Voyager 2 (followed a few weeks later by Voyager 1) wasn't obviously a big deal to most people. In fact, I wouldn't fully appreciate the change until sometime in 1980.

To understand why, a bit of history is in order. NASA had been sending probes to other planets, like the Mariner and Pioneer series, since the 1960s. However, even the best technology of the time was pretty limited in terms of what it could do remotely. And for most of that time, they were badly overshadowed by manned exploration, first the Apollo missions and Skylab, and later the planning for the space shuttle. In fact, even as the Voyagers flew past Jupiter, I seem to recall more attention being paid to the impending de-orbit of Skylab, which scattered charred pieces of itself over Australia later that year.

But for me, everything changed with the arrival of the January issue of National Geographic early the next year. Its picture, of an erupting volcano on Jupiter's moon Io, was simply stunning. The contents continued to amaze. Supersonic winds in Jupiter's atmosphere. Stunning photos of the Great Red Spot. Water ice reshaping the surface of Europa. I can't even begin to imagine how many times I reread the issue.

Further issues of the sort came as the Voyagers passed the other outer planets, but the Jupiter issue was the one that truly fulfilled the before-and-after promise held by the Voyagers' launch.

Reimagining science

I had always had an interest in science, going back to things like a childhood addiction to all things dinosaur and a love of PBS specials. But like most other kids, I had been operating under the distorted picture of science presented by the typical school textbooks at the time: make a hypothesis, do some direct tests, and draw a conclusion. The Voyagers turned all that upside-down.

Whoever wrote National Geographic's coverage brilliantly captured the fact that scientists sometimes do things just to see what's out there, rather than being driven by a specific hypothesis. And, quite often, they're actually surprised by what they find. Europa being nearly crater free? None of our previous planetary visits had suggested anything like that was going to be likely. Active volcanoes on a moon? That wasn't on the mission list.

In fact, the discovery of Io's volcanoes showed that serendipity played a part in science. If the narrative was right, they weren't even found during the observations that were directed at the moon. Instead, a camera simply meant to pick out stars for navigation purposes happened to capture an eruption while trying to get a fix on a nearby star.

It also became clear that the whole idea of science being all about direct tests needed a bit of revision. The Voyagers did have cameras and spectrometers that told us about the composition of various things they observed. But they also had magnetometers, that simply registered what was going on in their immediate environment. It was clear those readings could be plugged into models that told us something about the environment as a whole and, more broadly, what was going on at Jupiter and its moons to generate that environment.

And those models weren't static things that you tested, then either accepted or discarded. Tidal forces were quickly pinpointed as providing the heat that made Jupiter's inner moons such dynamic places, but the details were revised, argued over, and left with a fair degree of uncertainty attached. Other data was described even as it was made clear that there was no consensus about what could possibly explain it.

You can tell how much of an impression this made on me based on the fact that I still remember all of this over 30 years later.

Reimagining the Universe

But like the best of science, the Voyagers didn't just change their corner of science; they changed how we view the world.

It may be hard to imagine it now, but I had grown up at a time when we believed that the Earth was the only host of active volcanoes in the Solar System, and all of the bodies we'd explored had been so hostile that life wasn't a realistic option. Now, we regularly talk about the active geology of places like Io and Titan, and consider the relative prospects for life on various moons. The Voyagers completely changed the way we talk about the Solar System and, in the process, our place in it.

I don't think it's an exaggeration to say that the Voyagers have also shaped how we view the rapidly expanding catalog of planets outside our solar system as well. Rather than viewing them through the lens of Mars' barrenness or the hellish conditions of Mercury and Venus, the Voyagers made it possible to envision other worlds as part of a cacophony of different environments, including some we have not seen in our own Solar System. In fact, it wouldn't surprise me if the Voyagers didn't help inspire some people to look for planets elsewhere in the first place.

Now, over 30 years on, the Voyagers' greatest discoveries are part of the background of how I view science and the Universe. But they continue to amaze for one other reason: their longevity. NASA builds its hardware to survive incredibly harsh environments, so provided nothing goes badly wrong, it has become common for missions to still be going long after their expected finish. Even so, 35 years of operation and data sent back from the border of the space between the stars is just a staggering testament to the Voyagers' engineering.

They will probably never change the world again, but it's somehow nice to think that their scientific career has continued to span the entirety of one they helped inspire: mine.

Promoted Comments

I love this reminiscence, and the image of that Nat Geo cover brought on a wave of nostalgia for me. But, there's an important thread missing in this story: volcanism on Io was predicted shortly before Voyager 1's Jupiter encounter in this March 1979 paper, "Melting of Io by Tidal Dissipation":

From observations of the Laplace resonance in the orbits of Io, Europa, and Ganymede, the authors inferred extreme tidal heating and resulting volcanism on Io. Prescient words: "The surface of the type of body postulated here has not yet been directly observed, and although the morphology of such a surface cannot be predicted in any detail, one might speculate that widespread and recurrent surface volcanism would occur."

Amid all of the serendipitous scientific discoveries made by the Voyagers, there's an incredible story of predictive science.

I grew up in the 1980s with the phenomenal Voyager images of Uranus and Neptune as a backdrop. Seeing those hazy blue worlds, the wisps of high altitude cirrus on Neptune, ignited the young imagination.

For me, the Voyagers set the foundation of all modern planetary science. We knew nothing about the outer solar system before the Voyagers and thought we knew a lot of things which were completely false. The Voyager missions taught us to speculate less, as we got it so badly wrong, and send out probes to see for certain... Or just to raise more questions.

Volcanoes? Active volcanoes? On a mere moon? Oh yes, right there on Io. A surface so flat it can only be floating on a liquid, probably water? I've got your Europa right here. A dynamic weather system and a chemically complex and active atmosphere? That'll be Titan. If the planets are the crown of the solar system, the moons are its jewels.

Hopefully this stellar achievement will get some press today and help people realise the value of exploring the universe and NASA's ongoing hard work - rather than the waste of money some would try and paint them as.

When I was a kid it was the Voyagers, Carl Sagan (Cosmos) and a few teachers that helped me see a future beyond the miasma in which I was stuck. I was particularly intrigued by the concept of one of our probes actually *leaving the solar system... a rather attractive idea to me at the time. I often wondered where I would be 40 years down the road when they broke through to the galactic high seas (and sometimes hoped we may have already passed them by then).

Now that the Voyagers can sense the impending end of the heliopause and the incoming cosmic winds, I think I'm almost starting to... miss them. Yes, it brings a tear to my eye. Thanks for sharing the nostalgia.

I can remember reading back issues of National Geographic in my grandparent's house in the early 70's - before the Voyagers were launched. One article that I read several times detailed the plans for the Voyagers - I think it was from the August 1970 issue, but maybe it was April and maybe it was 1972 (those odd vagaries of memory :-) The focus of the article was how the coming planetary alignment would afford the very rare opportunity for a grand tour of all the planets and the two Voyagers would be sent for that.

Anyway, with all the wonder I had as to what might be discovered on the journey, when they launched I went to reread the article and felt a bit disappointed. You see, they'd planned to visit Pluto when that article was written and somewhere along the way, that part got dropped. The plan had been for one of the Voyagers, I forget which, to head straight to Pluto from Saturn. What a missed opportunity that was.

A great tribute to an amazing and inspiring human achievement. My moment of revelation and wonder happened when I was studying chemistry at university in 1984. I was going through back issues of science magazines in the dimly-lit periodical stacks of the library basement, when I came across a Voyager special issue of either Sci. Am. or Nature (I can't recall which). I was amazed and awed by those wonderful images of Jupiter and its moons. I returned several times to stacks to re-read the article, and have been keenly following the progress of the Voyager probes ever since.

Longevity: spot on. Utterly amazing. And we are still taken aback by how long beyond expected, the Mars rovers survived. (I can only wish some of our everyday home-use appliances were built that well.) While some around me have looked at the pics and reacted with zzzsnrkzzz, I've been like you, the whole way, waiting for more.

I can remember reading back issues of National Geographic in my grandparent's house in the early 70's - before the Voyagers were launched. One article that I read several times detailed the plans for the Voyagers - I think it was from the August 1970 issue, but maybe it was April and maybe it was 1972 (those odd vagaries of memory :-) The focus of the article was how the coming planetary alignment would afford the very rare opportunity for a grand tour of all the planets and the two Voyagers would be sent for that.

Anyway, with all the wonder I had as to what might be discovered on the journey, when they launched I went to reread the article and felt a bit disappointed. You see, they'd planned to visit Pluto when that article was written and somewhere along the way, that part got dropped. The plan had been for one of the Voyagers, I forget which, to head straight to Pluto from Saturn. What a missed opportunity that was.

I can remember reading back issues of National Geographic in my grandparent's house in the early 70's - before the Voyagers were launched. One article that I read several times detailed the plans for the Voyagers - I think it was from the August 1970 issue, but maybe it was April and maybe it was 1972 (those odd vagaries of memory :-) The focus of the article was how the coming planetary alignment would afford the very rare opportunity for a grand tour of all the planets and the two Voyagers would be sent for that.

Anyway, with all the wonder I had as to what might be discovered on the journey, when they launched I went to reread the article and felt a bit disappointed. You see, they'd planned to visit Pluto when that article was written and somewhere along the way, that part got dropped. The plan had been for one of the Voyagers, I forget which, to head straight to Pluto from Saturn. What a missed opportunity that was.

The Voyagers (and the images they sent back) are largely responsible for how much I love space exploration and NASA. From the truly awe-inspiring pictures of our gas giants to the ongoing story of longevity through ingenuity, I heart Voyager long-time.

Just read up on New Horizons, and its ongoing trip into (and hopefully beyond) the heliosphere. Would be great to get another probe up there!

Truly amazing stuff. This line from the NASA site makes my skin tingle:

" In about 40,000 years, Voyager 1 will drift within 1.6 light years (9.3 trillion miles) of AC+79 3888, a star in the constellation of Camelopardalis. In some 296,000 years, Voyager 2 will pass 4.3 light years (25 trillion miles) from Sirius, the brightest star in the sky . The Voyagers are destined—perhaps eternally—to wander the Milky Way."

Thanks for writing this article. Voyagers are really worth remembering and they are my favourite mission. You surely are not the only one whose interest in space exploration was spurred by these influential missions. At the time when I was child, their imagery and data was _the_ picture of outer solar system (and sadly, for Uranus and Neptune this still holds, even after 35 years). Of other unexpected discoveries I can recall out of my head was strange geology of Uranus' moon Miranda and unexpectedly active surface of Neptune's Triton.

But we should not forget that they were not the first to explore the outer Solar System. Pioneers 10 and 11 did it a few years earlier. The Pioneer 10 mission lasted about 30 years ("only" 22 years for Pioneer 11). They were the first man-made objects to leave the Solar System.

Not trying to steal any thunder from the 35th anniversary of the launch of Voyager 2, just offering a reminder of what came before.

I love this reminiscence, and the image of that Nat Geo cover brought on a wave of nostalgia for me. But, there's an important thread missing in this story: volcanism on Io was predicted shortly before Voyager 1's Jupiter encounter in this March 1979 paper, "Melting of Io by Tidal Dissipation":

From observations of the Laplace resonance in the orbits of Io, Europa, and Ganymede, the authors inferred extreme tidal heating and resulting volcanism on Io. Prescient words: "The surface of the type of body postulated here has not yet been directly observed, and although the morphology of such a surface cannot be predicted in any detail, one might speculate that widespread and recurrent surface volcanism would occur."

Amid all of the serendipitous scientific discoveries made by the Voyagers, there's an incredible story of predictive science.